I love my 18v mod. Not a terribly huge difference with distortions, but for clean sounds, I can't imagine not having it. EMGs are designed to be close to the strings, and with a guitar set up that way, a hard pick attack tends to drive the onboard preamp into distortion (that's nasty unintended distortion, not good distortion). Sounds similar to overdriving a preamp on a console, which is not generally the most pleasant thing to hear. The 18v mod takes care of that completely, and all my EMG pickups sound absolutely pristine now when clean, and just as brutal as before when driving a 5150 hard.